Comparative study of the crystallographic expansion of GSC and LSC porous electrodes

Abstract

Characteristics of the porous Gd 0.15 Sr 0.85 CoO 3−δ and La 0.6 Sr 0.4 CoO 3−δ cathodes were compared using the data measured at different electrode potentials and oxygen partial pressures. The electrochemical high-temperature in situ XRD (HT-XRD) method combined with electrochemical impedance spectroscopy has been used. The response of the crystallographic parameters and impedance values on the changes of electrode potential has been discussed. Reversible changes of the lattice parameters for both cathodes, slower for Gd 0.15 Sr 0.85 CoO 3−δ compared with La 0.6 Sr 0.4 CoO 3−δ , were observed depending on temperature (T), electrode potential (E), and oxygen partial pressure (pO 2 ). The crystallographic parameters are determined by the vacancy formation kinetics as well as by vacancy formation energy in/at the cathode grain structure. Calculated impedance data were fitted to the experimental data and characteristics were obtained in context of crystallographic changes of the cathode materials studied. K E Y W O R D Scathode characteristics, in situ XRD, solid oxide fuel cell INTRODUCTIONPerovskite-type ABO 3 complex oxides are of interest as catalysts for oxygen reduction reaction in solid oxide fuel cell (SOFC) cathodes, and as an anode in oxygen separation membranes. In solid oxide electrolysis mode, the above mentioned reaction is known as oxygen evolution reaction (OER) [1][2][3][4][5][6][7][8]. The properties of these materials, developed and discussed as most important ones for afore mentioned Abbreviation: EC, equivalent circuits; G, Gerisher impedance element; GDC, gadolinia-doped ceria (Ce 0.9 Gd 0.1 O 2-δ ); GSC, Gd 0.15 Sr 0.85 CoO 3−δ ; HT-XRD, high temperature X-ray diffraction; LSC, La 0.6 Sr 0.4 CoO 3−δ ; SOFC, solid oxide fuel cell; XANES, X-ray absorption near edge spectroscopy; W S , Generalized Finite Warburg elementThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Influence of A-Site Deficiency and Ca Concentration on the Electrical and Crystallographic Properties of (Nd0.2Sr0.7–xCax)yTi0.95Fe0.05O3−δ-Based Fuel Electrode for Solid Oxide Cells

“…and the B-site (such as Fe, Ni, etc.) of SrTiO 3 -based compounds offers the potential to enhance catalytic activity, electrical conductivity, and chemical stability of these materials. , It has been reported that among perovskite structures with lanthanoids (Ln), like La, Pr, Nd, Sm, and Gd as dopants in the A-site of Ln x Sr 1– x Co y Fe 1– y O 3−δ , the composition with Nd demonstrates the best electrical conductivity and very good catalytic activity for oxygen reduction . Additionally, Tamimi et al observed that materials incorporating Nd exhibited lower electrode impedance compared to those with La in Ln 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (Ln = La, Pr, Nd).…”